Thanks, everyone for your suggestions! We ended up buying from Off Road Express in Erie, Pa that one of you suggested. I wanted to try Suzuki because they have 0% APR for five years but my son, the racer really, really wanted the 2012 KX450F so that is what we ended up getting. I was swayed into the decision because of all the new features on the KX and also seeing it in person it seems to be a bigger/taller bike and my son at age 16 is already 6'2" and not done growing so it seems to be a good fit.
The guys at Off Road Erie were really good to deal with and gave us the best deal around!
Thanks again,
Roxanne